The present invention relates to a method and system for monitoring well cementing operations. More particularly, the present invention relates to a method and system for simultaneously monitoring pressure along the annulus of a well during cementing operations to determine whether remedial cementing is likely to be required.
Current and reliable information regarding conditions at zones of a formation can aid in completing wells. In such applications a borehole is drilled to cross multiple zones of a formation. Some of the intersected zones may contain hydrocarbon bearing strata or otherwise have a geopressure that may interfere with the ability of the cement job to effectively seal the borehole wall to the casing across the annulus unless the cement is properly matched to conditions along the annulus. Timely information indicating whether the seal is effective or not will permit prompt remedial action on this well and, perhaps, suggest redesign of the cement job in time for subsequent wells in the same field that are being cemented in batch operations.
A single downhole gauge may be placed to monitor conditions, e.g., pressure, at a given interval. This will provide current and reliable information, but only for a specific location and this may prove insufficient for well management purposes. Alternatively, commercial services provide "repeat formation testing" in which a wireline tool is run and multiple readings are taken as the tool is retrieved. This does provide data on multiple zones, but the information is not truly simultaneous and is collected only intermittently. These techniques are not practical for monitoring cementing operations.
Thus, there remains a clear need for a method and system for providing early indications of the likely effectiveness of a cement job in oilfield applications.